Hosiery fabric or the like and method of producing the same



Oct. 27, 1964 A BURLESON 3,153,923

HOSIEIRY FABRIC OR THE LIKE AND METHOD OF PRODUCING THE SAME Filed April 4, 1963 2 Sheets-Sheet 1 ATTORNEYS Oct. 27, 1964 A. BURLESON 3,153,923

HOSIERY FABRIC OR THE LIKE AND METHOD OF PRODUCING THE SAME Filed April 4, 1963 2 Sheets-Sheet 2 ATTORNEYS United States Patent 53153323 HGSZERY FABFQ {3R LEE AND (2F PRQDUCING THE SAME Aaron Bnrleson, Burlington, N.C., assignor to Eurlington industries, Ina, Greensboro, N.C., a corporation of Delaware Filed Apr. 4, 1963, er. No. 27%,592 17 Claims, (fil. 66-178) The present invention relates to knitting and in particular to an improved method of knitting with thermoplastic yarns such as nylon, polypropylene, or the like. The invention also relates specifically to the improvement of knitted fabric resulting from the method and even more specifically to tubular knitted fabric such as seamless ladies stockings.

This application is an improvement of the method and article disclosed in my prior United States Patents 3,055,- 197, and 3,055,198, both granted September 25, 1962.

in the circular knitting of seamless hosiery, a constant number of needles is utilized throughout the welt, le and foot. In order to shape the stockings to the contours of the leg, the stitch length is varied as the knitting proceeds. At the top of the stocking, as will be evident, the stitch is larger than in the ankle and foot areas. There are, however, limitations to the shaping of stockin s by means of stitch length variation. If the cylinder of the knitting machine is adequate in diameter to make a welt of generous size, the ankle and foot areas of the stocking are prone to be too large, tightening of the stitch in these areas being insufficient to narrow them down to desired relative size. if a knitting machine of smaller cylinder dia ieter is utilized, to produce a stocking of acceptable fit in the ankle and foot, the welt and knee areas of the stocking tend to be tight fitting. A compromise is usually effected, wherein the welt and knee areas are tighter than might be desired, and the ankle and foot areas looser. After knitting, seamless hosiery made of thermo lastic yarn can be further shaped by boarding, but the knee and welt areas still present a problem in that they have a tendency to be too tight.

One procedure heretofore utilized in overcoming the above problem is to pre-shrink or pre-set the welt yarn before knitting or more specifically before stitch formai tion so that there can be little or no welt shrinkage after the hose has been knit. As received from the manufacturer, thermoplastic yarn has a residual shrinkage, for example, nylon has about 6 to 25 percent residual shrinkage, whereas polypropylene has about 6 to percent residual shrinkag The Welt yarn was first shrunk by special treatment prior to knitting and then after knitting and during boarding the leg and foot were shrunk but the welt yarn was not shrunk. Pre-shrinkage of the Welt yarn before knitting increased its stifi'ness and introduced difliculties in forming loops properly on the knitting machine. Further, by only pre-shrinkage the welt yarn problems resulted in uneven dyeing, non-uniformity of stitches between welts and stitch breakdown, all of which lowered the quality of the stockings. Whfle improved fit may have been achieved in this manner, the manufacturing ditficulties encountered reduced the quality of the goods while increasing the cost of production. However, there was still some inflexibility in final shape and size.

In my above-mentioned patents, a knitting process and article produced thereby overcame certain of the roblems which resulted in the process of pre-shrinkage or pre-setting the welt yarn as described above. in more detail, my aforementioned patents disclose an invention in which stitch formation could be controlled when knitting with thermoplastic yarn by heating the yarn suiticiently to soften the same and then drawing the stitches in the yarn. However, cerain difficulties still existed in that the problem of knitting a seamless stocking having a large welt and yet a desirable fit in the ankle and foot areas was not completely satisfactory. There still had to be a compromise effected wherein the welt and nee areas were tighter than desired or the ankle and foot areas looser than desired.

A principal object of the present invention is to provide a novel method for producing a novel tubular knitted fabric whereby an improved fit may be made without affecting stitch formation and fabric clarity.

Ancillary to the preceding object, it is a further object of the present invention to provide a novel knitting method resulting in a novel seamless stocking having an improved shape and lit for a greater range of sizes. In other words, it is highly desirable to produce a seamless stocking in which there can be a large welt and yet a relatively smaller ankle and foot portion so that the stocking will have a shape capable of accommodating leg shapes heretofore not accommodated by conventional seamless stockings.

Still another obiect of the present invention is to provide an improved method of knitting with thermoplastic yarn wherein the fabric knitted has varying degrees or portions of the residual shrinkage of the yarn removed from one portion of the knitted fabric to an adjacent portion of the knitted fabric.

Another object of the present invention is to provide a seamless stocking which prior to the greige-shaping process has a decreasing amount of residual shrinkage removed from the yarn as it is knitted from the welt end toward the angle and foot end thereof. By such an arrangement, when the stocking is boarded there can be a very large amount of shrinkage in the foot and ankle area with a gradually decreasing amount of shrinkage in the knee and welt areas, thus giving a large degree of horizontal stretch between the knee and ankle area than has been attainable heretofore by either tightening the stitch in the angle area or by shrinkage in the welt area alone. With a combination of stitch tightening and variable degrees of shrinkage in the knitted fabric prior to boarding, the method of the present invention results in obtaining a dilferential and horizontal stretch between the knee and ankle areas that has not been achieved before in seamless thermoplastic stockings through stitch tightening alone.

These and other objects and advantages of the present invention will appear more fully in the following specification, claims, and drawings, in which:

FIGURE 1 is a perspective view of the latch ring and knitting station elements of a conventional seamless hosiery circular knitting machine, which view also discloses the novel arrangement for selectively varying the heat applied to the yarn just prior to its being knitted into the stocking; I

PEGURE 2 is a side elevational view of the mechanism of FIGURE 1 with the control means for the heating element eliminated, the view being partially broken away for purposes of clarity;

FIGURE 3 is a side elevational view of a seamless stocking knitted in accordance with the prior art and dis closing the greige shape before boarding;

FIGURE 4 is a side elevational view of a seamless stocking knit in accordance with the present invention and illustrating the greige shape before boarding with the graduated taper acquired by varying the percentage of shrinkage left in the yarn;

FIGURE 5 is a side elevational view of a seamless stocking knit in accordance with the present invention, the stocking having been boarded;

FIGURE 6 is an enlarged fragment of a representative '3? portion of the body fabric of the stocking of FIGURE and FIGURE 7 is a fragmentary view of a modification for controlling the heating element of FIGURES 1 and 2.

Referring to the drawings, FIGURE 1 illustrates a portion of a conventional seamless hosiery machine, which may be for example a 400-needle Model KN Scott & Williams machine. As shown, the latch ring 19 is pivotally mounted by means of pivot 12 between brackets 14 extending'upwardly from the bed plate (not shown) of the machine, and encloses the knitting station indicated generally as 16. At the knitting station, a plurality of yarn fingers 18 are provided, the yarn fingers being individually retractable, and functioning as interchangeable yarn feeds. The yarn fingers are pivotally mounted at 20 in the latch ring lug 22. A bracket 24 extends upwardly from latch ring lug 22, and from the outwardly turned bracket end 26 a tension spring 28 extends to the outer end of each yarn finger. On the opposite side of pivot 20, each yarn finger is engaged from below by a thrust bar 30, operative in conventional manner from the main drum of the machine.

The yarn fingers are normally maintained in up or inoperative position by their associated thrust bars, the springs 28 being thereby extended. Downward movement of any thrust bar, for example, to the position 30, permits the engaged spring 28 to displace the associated feed finger 18 to active position, as shown at 18' in FIGURE 2, whereby the feed finger is disposed in close proximity to the path of the knitting needles 32. In FIGURE 2 is also illustrated the dial drive pinion 34, adapted to drive the dial 36 and its transfer jacks 38 in synchronism with the rotary cylinder of the machine, and the independent needles 32 carried thereby. The dial is surmounted by the usual dial cap 40.

The customary yarn guide plate 42 is mounted on the latch ring lug 22, and extends over the yarn fingers 18. The yarn guide plate 42 is provided with a plurality of eyelets 44, and yarns 46 extend through eyelets 44 and the drilled inner ends of the yarn fingers 18. As shown in the drawing, yarns 46 extend to the inactive yarn fingers 18, and the yarn 46' extends to the finger 18' in operative or knitting position. All machine elements described to this point are conventional.

A heating element 50 is disposed between the yarn guide plate 42 and the yarn fingers 18, as by bracket 51 extending from the latch ring lug, and extends generally transversely of the yarn finger group. The heating element may be of any conventional type, but preferably is an electrical heating element, supplied with variable amounts of current by the conductor 54, as will be described in more detail later in the specification. The

heating element is desirably constructed of metal and smooth surfaced, preferably being chrome plated.

In my aforementioned United States patents, the heating element 50 was heated to a temperature of about 450 F. so that the travelling welt yarn was heated to a temperature above 220 F. to a temperature in the region of from about 220 to about 400 F. In other words, the yarn passed the heating elements 50 and was heated to a temperature so as to soften and relax the same and take out about one-half of the residual shrinkage as the yarn was passing from the yarn guide plate 42 to the needles of the machine. The heater 5!) was positioned close enough to the needles 39 so that the needles formed the stitches while the yarn was still hot and such softening of the yarn facilitated a uniform stitch formation and fabric clarity as shown in FIGURE 6. While the invention of my heretofore mentioned patents provided a method and article in which there was excellent uniform stitch shape and fabric clarity, the knitting method of heating the yarn to one temperature in the portions of the stocking where heat was desired did not produce the range for variation of shape and size which results in my present invention.

Referring again to FIGURE 1 of the drawing, it will be noted that conductor 54 is provided with a pair of wires 7%) and 72 leading respectively to a stepping relay generally indicated at 74 and to a transformer generally indicated at 76. The transformer 76 has a primary coil 78 connected to a suitable source of electric power as indicated at 80, for example, 110 volts alternating current. The secondary winding 82 has the wire 72 connected thereto at a tap 84. A plurality of taps 86, 88, 9t), and 92 are provided on the secondary winding 82 of transformer 71: in addition to the tap 84, these taps being connected respectively to terminals 4, 3, 2, and 1 of the stepping relay 74. The stepping relay 74 is also provided with the terminals 4, 3', 2' and 1 respectively connected to the terminals 4, 3, 2 and 1.

A microswitch 94 connected to the source of electric power 89 and to the stepping relay 74 controls the movement of a sweeping arm 96 in a direction of the arrow A. Microswitch 94 is actuated by lugs 98 selectively provided on links of the conventional pattern chain 100 of the circular knitting machine. The pattern chain 100 which controls the conventional pattern drum that in turn controls the stitches or courses, advances one link for each twelve courses knitted. The lugs 98 are suitably positioned on the pattern chain 109 so as to actuate the switch 94- when it is desired to selectively reduce the temperature of the heating element 50 during a predetermined portion of the knitting of the stocking for reducing the amount of residual shrinkage taken out of the thermoplastic yarn.

While FIGURE 1 discloses only four taps on the transformer connected to eight terminals on the stepping relay,

it will be appreciated by those skilled in the art that any number of taps and terminals and arrangement of connections between the same can be used for giving any selective number of changes in voltage to thereby vary the current to and temperature of the heating element a predetermined selective number of times.

FIGURE 7 discloses a modification for control of the heating element 50. In the modification shown in FIG- URE 7, the transformer 76' is a variable transformer having the usual sweep arm 102. The sweep arm which controls the output voltage is operatively connected to and moved by the contour of a templet 104. The templet 164 can have a contour shaped so as to provide a continuous change in temperature during the knitting of the stocking from the welt to the toe and, thus, rather than have a stepped change in temperature of the heat element 50 there can be a continuous change so that an even Wider range of shape may be selectively made in the knitted greige stocking before boarding.

The functions of the operation of the apparatus illustrated in the drawings will now be described, thus illustrating the method of the invention. At the beginning of the knitting operation all of the yarns are inactive, and extend through the respective eyelets 44 and feed fingers 18 to the dial cap 40 where they are clamped by the usual means, not shown. Upon initiation of welt knitting, the thrust rod 30 for the particular feed finger 18 having the welt yarn is lowered by movement of the main pattern drum of the machine and the yarn finger 18 thereby drops to an active or operative position (as shown at 18', FIGURE 2) under the impetus of its spring 28. The welt yarn, for example, 46' of FIGURE 2 is drawn over the heating element 50 and down between the hooks of the knitting needles 32 and taken in the hooks of the succeeding needles and, thus, welt knitting proceeds.

With the commencement of welt knitting, the sweep arm 96 of the stepping relay 74 moves onto terminal 1 and thus a predetermined amount of current is supplied through to wire 70 and 72 to the heating element 50. Since it is desirable to remove all or nearly all of the residual shrinkage from the welt yarn, the heating element 50 is heated up to a temperature of about 500 F.,

if the yarn is for example nylon, and this raises the temperature of the nylon yarn to about 375 F., and thus causes at least no more than 2 percent of the residual shrinkage to remain in the yarn. The heated yarn remains at the elevated temperature While passing through the yarn finger 18 and while engaged between the hooks of the needles 32 and through the stitch formation. The yarn remains hot while stitches are formed therein by the needle hooks and then cools and sets in knitted shape. Cooling and setting of the yarn during the welt knitting takes place usually after about one half revolution of the cylinder. The length of time for cooling will vary depending upon the temperature to which the yarn is elevated.

At the end of the knitting of the Welt, the thrust rod 39, which had been previously lowered, is elevated so as to raise the finger 18 for the Welt yarn to an inactive position, the welt yarn also being displaced away from the heating element. Substantially simultaneous with this operation, a body yarn 45 is dropped into the knitting and the knitting of the leg proceeds. With the dropping of the body yarn 46 into the knitting, there is further movement of the sweep arm 96 as the microswitch 94 will have been again actuated by another lug 98 on the pattern chain 100. The movement of the sweep arm 95 from terminal 1 to terminal 2 on the stepping relay 74 will reduce the voltage and current supply to the heating element 50 and thus the body yarn will not be pre-shrunk as much as the welt yarn.

Throughout knitting of the leg of the stocking, the lugs on the chain 100 will periodically actuate the switch 94 so that the sweep arm 96 will successively proceed to the other taps thus further reducing the current to the heating element 50 and temperature of the yarn so as to progressively decrease the amount of residual shrinkage taken out of or removed from the yarn as the knitting of the leg approaches the ankle, heel and foot portion. When the knitting reaches the ankle portion, practically all of the residual shrinkage is left in the yarn so that there can be a maximum amount of differential between the welt and the ankle, heel and foot portion after boarding. Since it is desirable to have practically all of the residual shrinkage in the yarn knitted into the ankle and/ or foot portion of the stocking, the yarn is heated to a temperature of 220 F. or below if the yarn is nylon, as the range of temperature for removing residual shrinkage is 220 F. to about 400 F.

Referring now to FIGURE 3, the conventional stocking 52 knitted on a circular knitting machine is disclosed in greige shape before boarding. It will be noted that the stocking has a welt 54, a leg 56, which are generally cylindrical, an ankle portion 57, which is knit of a smaller diameter than the leg portion 56 by tightening up on the stitches in the area 59. A foot portion 58 has about the same diameter as the ankle 59 and the usual heel 60 and toe 62 are provided thereon.

Referring next to FIGURE 4, it will be noted that the stocking 52 of the present invention has a welt 54' which has a greater diameter than any portion of the stocking and a gradually tapering leg portion 56, a foot portion 53, a heel portion 6%) and a toe 62. The stocking of FIGURE 4 knitted according to the method of the present invention provides for a better fit after boarding as the knee and ankle areas of the stocking can be shrunk to a smaller size than could be accomplished by just tightening of the stitches alone. The stocking 52' made according to the present invention has the advantage over prior stockings made on circular knitting machines or stockings made according to the method disclosed in my aforementioned patents in that it can be made into many various shapes and sizes so as to provide an improved fit for irregular shaped legs. In other words, the stocking 52' of the present invention can be made to have a welt 54' which will fit legs having eX- tremely large thighs and yet the stocking can still have a proper fit in the knee and ankle areas especially if the selective pre-shrinking is coupled with the usual stitch tightening. It is also contemplated that the present method may be used in knitting surgical stockings as a very accurate control of the shape can make the stockings have the necessary support in selected areas where needed. By knitting the stocking while the yarn is still hot from the selective pre-shrinking, the stocking 52' of the present invention also maintains the same advantage of the stocking in my aforementioned patents in that there is uniform stitch shape and fabric clarity. This is evident by observance of FIGURES 5 and 6 which illustrate respectively the finished stocking after boarding with its large welt 54' and the appearance of body yarn 64, characterized by the loops having uniformly excellent shape and the fabric having excellent clarity. Since the entire stocking is knit while the yarn is softened, the welt 54 as well as the ankle 57' and foot 53' will also have uniform stitch shape and fabric clarity.

When the stocking of the present invention is made from polypropylene yarn, it is usually received from the manufacturer having 6 to 40 percent residual shrinkage. The temperature range for removing a portion of the residual shrinkage to about all of the residual shrinkage from polypropylene yarn is from about 200 to 385 F. Of course, the temperature of the heating element 56 will have to be varied accordingly to obtain the selective shrinking of polypropylene yarn. Other thermoplastic yarns having residual shrinkage therein may be used in the practice of the novel method of the present invention to produce the novel stocking, it being understood that the temperature ranges for the particular thermoplastic yarn used will have to be determined so that the selective heating of the heating element may be properly made.

The particular means described and illustrated for graduated controlling of the heating element 50 and the particular type of heating element 51? described and illustrated may be varied without departing from the spirit and scope of the present invention. It is necessary only that the thermoplastic yarn be heated to the selected temperature at the proper time with respect to the portion of the stocking being knitted and in close proximity to the yarn feed and needles so that it remains softened while stitches are formed therein.

Vfhile the invention has been illustrated in connection with a circular hosiery knitting machine for knitting a seamless stocking, it will be evident that the invention may be utilized in connection with other types of knitting machines for knitting other types of knitted fabrics which may or may not be tubular but in which it is desired to selectively vary the amount of residual shrinkage remaining in the reige fabric prior to a final greige shaping process such as boarding.

It will thus be seen that there has been provided by this invention a machine in which the various objects hereinbefore set forth, together with many practical advantages are successfully achieved. As various possible embodiments may be made of the several features of the above invention, all without departing from the scope thereof, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative, and not in a limiting sense.

What is claimed is:

l. A method of knitting fabric of thermoplastic yarn comprising the steps of: heating the yarn to a temperature sufficient to soften and remove at least a majority of the residual shrinkage therefrom, drawing stitches with the yarn While so softened to form a portion of knitted fabric, then heating the yarn to a temperature sufiicient to soften and remove a lesser amount of residual shrinkage therefrom, and drawing stitches in the yarn while so softened to form another part of the knitted fabric.

2. A method of knitting tubular fabric of thermoplastic yarn comprising the steps of: heating a portion of the yarn to a predetermined temperature just prior to knitting suflicient to soften and remove at least some of the residual shrinkage therefrom and drawing stitches in the yarn while so softened, then heating another portion of the yarn to a different predetermined temperature just prior to knitting sufiicient to soften and remove a different amount of residual shrinkage and drawing stitches while this yarn is so softened to form another portion of the knitted fabric with a different amount of residual shrinkage.

3. A method of knitting tubular fabric of thermoplastic yarn comprising the steps of: heating the yarn prior to knitting by progressively decreasing temperatures suflicient to soften and remove progressively decreased amounts of residual shrinkage from the yarn, and drawing stitches in the yarn while so softened with the fabric knitted being provided with a progressively increased amount of residual shrinkage.

4. A method as claimed in claim 3 wherein the step of progressively decreasing the temperature is accomplished in stepped increments throughout the knitting.

5. A method of knitting as claimed in claim 3 where-' in the step of progressively decreasing the temperature is accomplished in a gradual uniform curve throughout the knitting.

6. A method of knitting seamless stockings comprising the steps of: heating the yarn during wel-t knitting to a temperature sufficient to soften and remove all but approximately 2 percent of the residual shrinkage and drawing stitches while the yarn is softened, heating the yarn during remainder of knitting of the stocking by a temperature which is gradually reduced while knitting the leg, ankle, heel and foot portion so that there is a graduating increase in residual shrinkage in the stocking from the welt toward the toe.

7. A method as claimed in claim 6 including reducing the temperature below the temperature necessary for shrinkage during knitting of the stocking in the ankle, heel, and foot portion.

8. A method as defined in claim 6 wherein the thermoplastic yarn is nylon.

9. A method as defined in claim 6 wherein the thermoplastic yarn is polypropylene.

10. A method of knitting seamless nylon stockings comprising the steps of: heating the yarn during welt knitting to a temperature of about 300 F. at which the yarn is softened and pre-shrunk to have a residual shrinkage of about 2 percent and drawing stitches in the yarn while so softened, heating the yarn during the remaining knitting of the stocking with the temperature being initially about 300 F. and gradually reduced to about 200 F. at which the yarn is softened and a progressively lesser amount of residual shrinkage is removed therefrom and drawing stitches in the yarn while so softened to form the remaining portion of the stocking.

11. A method of knitting seamless polypropylene stockings comprising the steps of: heating the yarn during welt knitting to a temperature of about 300 F. at which the yarn is softened and pre-shrunk to have a residual shrinkage of about 2 percent and drawing stitches in the yarn while so softened, heating the yarn during the remaining knitting of the stocking with the temperature being initially about 300 F. and gradually reduced to about 200 F. at which the yarn is softened and a pro: gressively lesser amount of residual shrinkage is removed. therefrom and drawing stitches in the yarn while so softened to form the remaining portion of the stocking.

12. in the operation of a circular knitting machine having a rotary cylinder with independent needles and a yarn feed operative adjacent the path of said needles, the method comprising the steps of: applying heat to said yarn in a selectively decreasing amount at a point in close proximity to the yarn feed suiiiciently that the yarn is softened and a progressively decreasing amount of residual shrinkage is removed therefrom, and draw ing stitches in the yarn by means of feed needles while the yarn is still softened.

13. A seamless stocking having a welt, leg, ankle, heel and foot portion made from a thermoplastic yarn, said stocking having a residual shrinkage of approximately 2 percent in the welt and a progressively increasing amount of residual shrinkage in the leg, ankle, heel and foot portion prior to boarding.

14. A seamless stocking as claimed in claim 13 made of nylon.

15. A seamless stocking as claimed in claim 13 made of polypropylene.

16. A seamless stocking having a welt, leg, ankle, heel and foot portion made from thermoplastic yarn, said sticking having a residual shrinkage progressively varying from approximately 2 percent in the welt to approximately full residual shrinkage in the ankle, heel, and foot portion prior to boarding.

17. A seamless stocking having a welt, leg, ankle, heel, and foot portion made from a thermoplastic yarn, said stocking being characterized by uniform stitch shape, fabric clarity, and having a progressively increasing amount of residual shrinkage in the yarn throughout the leg from the welt to the foot portion prior to boarding. V 7 References Cited by the Examiner UNITED STATES PATENTS 2,396,166 3/46 Faucette a 66178 2,485,230 10/49 Alexander et a1. 66-125 3,120,049 2/64 Spurgeo'n 66125 3,132,496 5/64 Berg 66-202 FOREIGN PATENTS 23 8,477 5/62 Australia. 1,23 2,790 4/60 France.

RUSSELL c. MADER, Primary Examiner.

DONALD w. PARKER, Examiner. 

17. A SEAMLESS STOCKING HAVING A WELT, LEG, ANKLE, HEEL, AND FOOT PORTION MADE FROM A THERMOPLASTIC YARN, SAID STOCKING BEING CHARACTERIZED BY UNIFORM STICH SHAPE, FABRIC CLARITY, AND HAVING A PROGRESSIVELY INCREASING AMOUNT OF RESIDUAL SHRINKAGE IN THE YARN THROUGHOUT THE LEG FROM THE WELT TO THE FOOT PORTION PRIOR TO BOARDING. 